Sprinkler and water circulating systems are utilized for watering lawns, golf courses and agricultural areas which incorporate a plurality of various types of water distributing heads attached to underground or above ground piping systems. Normally these systems provide manually or automatically operable valves at selected points to control water flow to groups of sprinklers, bubblers or the like. These may be operated by timers which permit water flow for predetermined time periods. In any event these valves remain open during such a time period so that if for any reason the sprinkler head is displaced, unrestricted water flow and loss of sprinkling effect and wastage of water may occur. Such displacement may result from impact upon a protruding head by a gardner or a mower, by loosening of a joint, breakage of a conduit or nipple, or other damage. Since such systems are usually unattended and may rely upon automatic timing systems, it is obvious that some means for preventing undesired flow upon disruption of the sprinkler head would be desirable.
In the prior art, as shown by U.S. Pat. No. 2,980,125, a valve is provided which will close upon impact by breakage of a barrel which supports a valve stem. In U.S. Pat. No. 4,064,889, a spring loaded normally open valve is closed upon breakage of a conduit having a weakened portion. However, such devices are not suitable for use in sprinkling systems of the type considered herein since replacement of broken conduits is costly and time consuming, and since in most cases, the problem of sprinkler displacement occurs through damage to or loosening of the sprinkler head itself rather than the conduit to which it is attached.